Kernel: Change HandlerPurpose to HandlerType

Also, GenericInterruptHandler class requires to implement two new
methods.

Kernel/Devices/FloppyDiskDevice.h

@@ -172,6 +172,8 @@ public:
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override { return 0; }
     virtual bool can_write(const FileDescription&) const override { return true; }
 
+    virtual const char* purpose() const override { return "Floppy Disk Controller"; }
+
 protected:
     explicit FloppyDiskDevice(DriveType);
 

Kernel/Devices/HardwareTimer.h

@@ -32,7 +32,6 @@ namespace Kernel {
 class HardwareTimer : public IRQHandler {
 public:
     u32 seconds_since_boot();
-
 protected:
     HardwareTimer(u8 irq_number);
     u32 m_seconds_since_boot { 0 };

Kernel/Devices/KeyboardDevice.h

@@ -57,6 +57,8 @@ public:
     virtual ssize_t write(FileDescription&, const u8* buffer, ssize_t) override;
     virtual bool can_write(const FileDescription&) const override { return true; }
 
+    virtual const char* purpose() const override { return class_name(); }
+
 private:
     // ^IRQHandler
     virtual void handle_irq(RegisterState&) override;

Kernel/Devices/PATAChannel.h

@@ -72,6 +72,8 @@ public:
     RefPtr<PATADiskDevice> master_device() { return m_master; };
     RefPtr<PATADiskDevice> slave_device() { return m_slave; };
 
+    virtual const char* purpose() const override { return "PATA Channel"; }
+
 private:
     //^ IRQHandler
     virtual void handle_irq(RegisterState&) override;

Kernel/Devices/PIT.h

@@ -58,6 +58,8 @@ public:
     static PIT& the();
     u32 ticks_this_second() const;
 
+    virtual const char* purpose() const override { return "System Timer"; }
+
 private:
     PIT();
     // ^IRQHandler

Kernel/Devices/PS2MouseDevice.h

@@ -47,6 +47,8 @@ public:
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
     virtual bool can_write(const FileDescription&) const override { return true; }
 
+    virtual const char* purpose() const override { return class_name(); }
+
 private:
     // ^IRQHandler
     void handle_vmmouse_absolute_pointer();

Kernel/Devices/SB16.h

@@ -50,6 +50,8 @@ public:
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
     virtual bool can_write(const FileDescription&) const override { return true; }
 
+    virtual const char* purpose() const override { return class_name(); }
+
 private:
     // ^IRQHandler
     virtual void handle_irq(RegisterState&) override;